Re: [PATCH v2] Documentation: gpio: consumer: describe the con_id parameter

[Dirk Behme <dirk.behme@gmail.com>]

On 21.07.2015 07:12, Alexandre Courbot wrote:
> On Sat, Jul 18, 2015 at 3:24 PM, Dirk Behme <dirk.behme@gmail.com> wrote:
>> The con_id parameter has to match the GPIO description and is automatically
>> extended by the GPIO suffix if not NULL. I had to look into the code to
>> understand this and properly find the GPIO I've been looking for, so document
>> this.
>>
>> Signed-off-by: Dirk Behme <dirk.behme@gmail.com>
>> Acked-by: Alexandre Courbot <acourbot@nvidia.com>
>> ---
>> Changes in v2: Incorporate the review comments from Alexandre.
>>
>>   Documentation/gpio/consumer.txt | 13 +++++++++++++
>>   1 file changed, 13 insertions(+)
>>
>> diff --git a/Documentation/gpio/consumer.txt b/Documentation/gpio/consumer.txt
>> index 75542b9..5f7437b 100644
>> --- a/Documentation/gpio/consumer.txt
>> +++ b/Documentation/gpio/consumer.txt
>> @@ -39,6 +39,19 @@ device that displays digits), an additional index argument can be specified:
>>                                            const char *con_id, unsigned int idx,
>>                                            enum gpiod_flags flags)
>>
>> +The con_id string parameter has to be either NULL or the prefix of the GPIO
>> +suffixes ("gpios" or "gpio", automatically looked up by the gpiod functions
>> +internally):
>> +
>> +* If the GPIO description is just named with one of the GPIO suffixes
>> +  ("gpios" or "gpio"), use NULL.
>> +* If the GPIO description is prefixed with anything, e.g. "reset-gpios", use the
>> +  prefix without the "-" as con_id parameter (in this example "reset").
>> +
>> +In case con_id is not NULL, the GPIO subsystem prefixes the GPIO suffix
>> +("gpios" or "gpio") with the string passed in con_id to get the resulting string
>> +(snprintf(... "%s-%s", con_id, gpio_suffixes[]).
>
> Ah, there is still an issue with this description. It is correct as
> far as GPIOs are assigned by the device tree ; but it turns out that
> we have two other ways of assigning GPIOs: ACPI and platform data.
> Have a look at the board.txt file which describes how this works. And
> actually, instead of repeating the same stuff in consumer.txt, maybe
> we can just redirect the reader to the other file?


Please have a look to

http://article.gmane.org/gmane.linux.kernel.gpio/9816

http://article.gmane.org/gmane.linux.kernel.gpio/9815

They should replace this patch, then.

Best regards

Dirk